Performance Optimization of VoIP using an Overlay Network
Raj Kumar Rajendran, Samrat Ganguly, Rauf Izmailov, Dan Rubenstein · 2005
Abstract — Voice traffic on the Internet (VoIP) is poised to grow rapidly but the Internet is not engineered for such delay-sensitive applications. We show how the end-user quality of VoIP calls can be improved by rerouting them in an intermediate overlay network and thought the use of various path-diversity and error-coding techniques. We introduce our overlay network (OverPhone) that is tuned to optimize VoIP quality and provide experimental results of its implementation on the PlanetLab testbed. We show that re-routing VoIP calls through OverPhone improves the quality of more than a third of the paths by significant amounts when using the G.711 codec. We believe that this benefit extends to other well known and proprietary codecs as well. We also investigated the benefits and trade-offs of using techniques such as path-diversity and paritycoding. We found that path-diversity is useful in sustaining throughput at high loads, and that parity-codes can be used to trade-off bandwidth for path-quality.